Camera system

ABSTRACT

A camera in which the film speed data and exposure time data are selectively indicated by a first indicator and aperture value data and override data are also selectively indicated by a second indicator.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional application of Application Serial No. 043,758, nowU.S. Pat. No. 4,763,144, filed April 29, 1987, which in turn was adivisional application of Application Serial No. 888,600, filed July 23,1986, now U.S. Pat. No. 4,712,904, which in turn was a divisionalapplication of Application Serial No. 634,474, filed July 25, 1984, nowU.S. Pat. No. 4,621,914.

BACKGROUND OF THE INVENTION

1. Field of the Invention:

The present invention relates to a photographic camera capable offunctioning with stored data such as, for example, stored data on thefilm speed.

2. Description of the Prior Art:

For the purpose of setting the film speed in a photographic camera, ithas been proposed to provide a surface of a film cartridge with a codepattern comprised of particular combinations of conductive andnon-conductive areas in correspondence with the film speed. When such afilm cartridge is loaded in the camera, a plurality of feelers providedin the camera detect such a particular combination of conductive andnon-conductive areas to set the film speed automatically in the camera.

SUMMARY OF THE INVENTION

An object of the invention is to provide a camera in which a pluralityof kinds of exposure data are simply indicated.

Another object of the invention is to provide a camera in which aplurality of kinds of exposure data can be indicated by simpleindicating means.

Yet a further object of the present invention is to provide a camera inwhich complex indication of a plurality of kinds of exposure data can beimproved.

FIG. 1 is a perspective view of a camera system according to a preferredembodiment of the present invention;

FIG. 2 is a diagrammatic view showing a relationship between a loadedfilm cartridge and feelers for reading data provided on the filmcartridge;

FIG. 3 is a diagrammatic view showing a mechanism of a frame-numbercounter;

FIGS. 4a and 4b, taken together as shown in FIG. 4, show a circuitdiagram employed in the camera system of FIG. 1;

FIG. 5 is a circuit diagram showing a detail of a circuit CIM of FIG.4a;

FIG. 6 is a circuit diagram showing a detail of a circuit CAD and acircuit EM of FIG. 4a;

FIG. 7 is a flow chart of a microcomputer provided in the camera body,particularly showing the operations for the initial setting;

FIG. 8 is a flow chart particularly showing the operation when the backlid is closed;

FIG. 9 is a flow chart showing the detailed steps for step #4 of FIG. 7or #8 of FIG. 8;

FIG. 10 is a flow chart showing the detailed steps for step #7 of FIG. 7or #10 of FIG. 8;

FIGS. 11a to 11h show a flow chart for the camera control under variousoperating modes;

FIG. 12 is a circuit diagram showing the details of a display controlDPC of FIG. 4b;

FIG. 13 is a flow chart similar to FIG. 7, but showing a modificationthereof; and

FIGS. 14a and 14b are plan views of a display employed in the presentinvention.

DETAILED DESCRIPTION OF THE EMODIMENT

The present invention will now be described in connection with apreferred embodiment thereof with reference to the accompanyingdrawings.

Referring first to FIG. 1, a camera body 1 is shown as having a releasebutton 2 which actuates a light measuring switch S1 for instructing alight measurement when it is depressed halfway and actuates a releaseswitch S2 when it is depressed fully for actuating a shutter.

Reference numeral 3 represents a mode change-over switch employed in theform of a slide switch, movable to P, S, M and A positions: P positionrepresents a programmed mode; S position represents an exposure timepriority mode in which the aperture is automatically controlled; Mposition represents a manual mode; and A position represents an aperturepriority mode in which the exposure time is automatically controlled.Reference numeral 4 represents a display section for displaying acontrol exposure time, an aperture value, a film sensitivity, and anoverride data. An example of the display is shown in FIG. 14.

Reference numeral 5 represents an aperture value setting key, referencenumeral 6 represents a shutter speed setting key, and reference numerals7 and 8 represent up-shift and down-shift keys for changing the value ofa selected item, such as aperture value F or shutter speed SS. A counterdisplay window 9 displays the number of film frames photographed.

Reference numeral 10 represents an ISO mode key. When this ISO mode key10 is depressed, ISO data utilized in the camera body 1 are displayed onthe display section 4 and can be changed at any time by means of theup-shift and down-shift keys 7 and 8.

Reference numeral 11 represents an override key. When this override key11 is depressed, override data are displayed on the display section 4and can be changed at any time by the manipulation of the up-shift anddown-shift keys 7 and 8. Reference numeral 13 represents a filminformation display window provided in a back cover 13 of the camerabody 1.

Within the camera body 1 shown in FIG. 1, there is provided, as shown inFIG. 2, code read-out feelers 15 and 16 for reading the ISO dataprovided on a film cartridge 14. These feelers 15 and 16 have aplurality of feeler pieces AT2-AT6, FT8, FT9, FT10, RT11, and RT12 (FIG.6) adapted to contact code electrodes K1 to K10 formed on the outerperipheral surface of the film cartridge 14, for example, in a matrix ofsix rows and two columns.

Each of these feeler pieces AT2 to RT12 are fixed by means of vices to apost 18 made of an insulating material and planted within the camerabody 1.

As shown in FIG. 3, within the camera body 1, there is provided aback-lid detecting switch 31 adapted to be opened and closed when a backlid 33 of the camera is closed and opened, respectively, and a counterswitch 32 associated with a film counter 34. The counter switch 32 isselectively closed and opened by a lever 36, driven by a cam 35, and isclosed when the count of the film counter shows a value within the rangeof S to 1 and it is opened when it shows a value more than 1.

FIG. 4 illustrates a block diagram of the entire camera system embodyingthe present invention. Reference character PO1 represents a power-onreset circuit provided with a battery power source BAB and adapted tooutput a power-on reset signal from a terminal PR1 when the supply ofelectric power from a power line VC is re-initiated.

Reference character MCB represents a microcomputer for controlling theoperation of the entire camera system. The operation of thismicrocomputer MCB is shown in the flow charts of FIGS. 7 to 10 and FIGS.11a to 11h. Reference numeral S1 represents a light measuring switchadapted to be closed upon the halfway depression of the release button2. Reference character ISS represents a switch adapted to be closed uponthe depression of the ISO mode key, and reference character ORSrepresents a switch adapted to be closed upon the depression of theoverride key 11. Reference characters FSS and SSS represent respectiveswitches adapted to be closed upon the depression of the aperture valuesetting key 5 and the exposure time key 6. Reference characters UPS andDOS represent switches adapted to be closed upon the depression of theup-shift key 7 and the down-shift key 8, respectively. Reference numeralRES represents a switch adapted to be closed upon the depression of arecall button 12. These switches are constituted in a key-matrix withoutput terminals O2, O3 and O4 and input terminals i1, i2 and i3 ofmicrocomputer MCB, and the one(s) which is(are) closed can bediscriminated by microcomputer MCB.

Microcomputer MCB is such that, when it is not operated, outputterminals O2, O3 and O4 are "High" and a line connected to inputterminal i1 is inputed to an interruption terminal itA through an ANDcircuit AN1, and OR circuit OR1, and AND circuit AN3. Accordingly, whenone of the light measuring switch S1, the ISO switch ISS and theoverride switch ORS is closed, interruption is effected to terminal itAand microcomputer MCB is then started.

Reference character BMS represents a main switch. When this main switchBMS is opened, an inverter IN2 produces "Low", thereby turning themicrocomputer in an inoperative position. Furthermore, AND circuit AN3is held in a disabled state and no interruption signal is inputed toterminal itA, with the microcomputer consequently not started. Inaddition, when battery BAB is removed to provide no power supply to lineVC, AND circuit AN3 is again held in a disabled state, thereby effectingno interruption. Accordingly, when battery BAB is not loaded or whenmain switch BMB is opened, microcomputer MCB remains in the inoperativeposition.

Switch S2 is a switch adapted to be closed upon the full depression ofrelease button 2. When this release button switch S2 closes, inverterIN3 produces "High" and an interruption signal is inputed to terminalitA through AND circuit AN2, OR circuit OR1 and AND circuit AN3. Whenthis interruption signal is inputed, and when a shutter charge hascompleted and the calculation of exposure control data has alsocompleted, an exposure control operation is immediately carried out. Itis, however, to be noted that, so long as the microcomputer is carryingout a data exchange with other circuits, OR circuit OR3 produces "High",causing AND circuit AN2 to be disabled. Thus, the interruption byrelease button switch S2 will not take place.

A switch RCS is a back-lid switch (corresponding to switch 31 in FIG. 3)adapted to be opened and closed when the camera back lid 33 is openedand closed, respectively. Accordingly, when the back lid is closed, theoutput of an inverter IN4 becomes "High" and a pulse is outputed from aone-shot circuit OS1 to set a flip-flop FR1, with an interruption signalconsequently inputed to a terminal itB. Then, microcomputer MCB performsan operation which is to be performed when the back lid is closed. Afterthis operation has been performed, a pulse is outputed from a terminalO18 to reset flip-flop RF1 thereby establishing the inoperativecondition.

Reference character LE represents an interchangeable lens assembly whichis electrically connected to the camera body through connectors CNF andCNB1 so that fixed data stored in a circuit LEC inside the lensassembly, such as an aperture value, can be serially applied tomicrocomputer MCB through an interface circuit BOL. This operationcauses microcomputer MCB to produce "High" from terminal O5. Then, whena serial-in and serial-out command is executed, eight clock pulses areoutputed from a serial clock pulse terminal SCP. In synchronism withthese clock pulses, data from the lens assembly LE are inputed and areread in from a serial input terminal SIN. By repeating this serial inputcommand a number of times, necessary data from the lens LE can be allread in.

Reference character CAD represents a code pattern circuit for outputingdata of the code pattern provided on the film cartridge 14. Referencecharacter EM represents a code plate for outputing data corresponding toa selected exposure control mode, and reference character SFC representsa counter switch (corresponding to that shown by 32 in FIG. 3) adaptedto be closed when the film counter is in a preparatory winding position,but opened when it is in a photo-taking position.

Reference numeral BUB represents a back-up battery. Reference characterCIM is a circuit for storing the ISO data, and for reading data CAD fromthe film cartridge, mode data and a signal from the flim counter switchSFC, the details of which are shown in FIG. 5. This circuit CIM ispowered by the back-up battery BUB through a diode D21 and is alsopowered by the main battery BAB through diode D20. Reference characterBCC represents a circuit for checking the output voltage of the back-upbattery BUB and is powered by a power line VB through a transistor BTOsuch that, when the output of the back-up battery BUB is higher than apredetermined value, BCC generates a "High" signal to a terminal i20.Reference character PO5 represents a power-on reset circuit capable ofoutputing a reset signal when the back-up battery is loaded. The resetsignal is fed only to an ISO data storage register within the circuitCIM, the content of said register being reset only when the back-upbattery BUB is loaded. Terminals O30, O31, O32 are terminals forproducing signals that control the operating mode of the circuit CIM. Inthe circuit CIM, an operation corresponding to output from theseterminals takes place. An OR circuit OR50 receives signals from theseterminals O30, O31 and O32, and its output terminal is connected to oneinput terminal of OR circuit OR3. Accordingly, when data transmission iseffected between circuit CIM and microcomputer MCB, interruption toterminal itA by release switch S2 is inhibited.

Referring to FIG. 5, reference character SD1 represents a circuit forreading, in synchronism with the clock pulses from a terminal SCP, datawhich are serially inputed from a terminal SOU of microcomputer MCB. Acounter LPC which operates when terminal O30 is "High", counts thenumber of synchronizing clock pulses when terminal O30 becomes "High",and outputs a latch pulse when it has counted eight clock pulses. Thislatch pulse is fed to a register LAC and, when this pulse is inputed,data from the reading circuit SD1 are latched. Register LAC is adaptedto be reset by a pulse fed from the power-on reset circuit PO5 shown inFIG. 5.

Reference character DSC represents a data selector. Its operation issuch that, when the signal from terminals O31 and O32 is "01", ISO datastored in the register LAC, as applied to an input section d1 isproduced. When the signal from terminals O31 and O32 is "10", the dataon the film container as applied to an input section d2 is produced.When the signal from terminals O31 and O32 is "11", the data of theselected mode and the data of counter switch as applied to an inputsection d3 are produced. In addition, when the signal from terminals O31and O32 is "00", the data selector DSC produces no data. A serial dataoutput circuit SDO sequentially serially outputs, when the output of anOR circuit OR52 becomes "High", data from the data selector DSC toterminal SIN on the basis of the synchronizing clock pulses.

The details of each of CAD and EM are shown in FIG. 6. Referring now toFIG. 6, the film cartridge 14 is provided with code patterns K1 to K12.Portions K1 and K7 are always formed with electrically conductivematerial regardless of the type of film cartridge and, in theillustrated embodiment, an electrode COT connected to the groundcontacts them. Portions K2 to K6 are provided with conductive andnon-conductive patterns according to the data corresponding to the ISOsensitivity of a film within the film cartridge 14, an example of whichis shown in Table 1.

Contact pieces AT2 to AT6 contact portions K2 to K6, respectively, andare connected to input terminal d2 of data selector DSC, shown in FIG.5, through pull-up resistors and inverters. Portions K8 to K10 areprovided with code patterns corresponding to the data of the number offrames of the film contained in the film cartridge 14. Although contactpieces FT8, FT9 and FT10 contact these portions, data from these contactpieces are inputed nowhere because, in the illustrated embodiment, thesedata are not utilized.

Portions K11 and K12 are provided with exposure range data.

Contact pieces RT11 and RT12 contact these portions K11 and K12 forsupplying data on portions K11 and K12 to input terminal d2 of dataselector DSC through pull-up resistors and inverters.

Reference characters Mt1, Mt2 and CMT represent data output code platesfor producing data which represents various exposure calculation modes.A slide member VT is moved in accordance with the movement of the modechangeover switch 3. When slide member VT is moved to the P positionrepresenting the programmed mode, data "00" are applied to inputterminal d2 of data selector DSC. When slide member VT is moved to the Sposition representing the exposure time priority mode (hereinafterreferred to as S mode), data "01" are applied to input terminal d2. Whenslide member VT is moved to the A position representing the aperturepriority mode (hereinafter referred to as A mode), data "10" are appliedto input terminal d2. When slide member VT is moved to the M positionrepresenting the manual mode, data "11" are applied to input terminald2. In addition to these data, a signal from film counter switch SFCthrough an inverter IN5 is also applied to input terminal d2 of dataselector DSC.

Referring back to FIG. 4, reference character FL represents a flashdevice in which a power source battery BAF, a firing and control circuitFLC and a main switch FMS are incorporated. Flash device FL is providedwith a connector CNF which, when flash device FL is mounted on thecamera body, is electrically connected with a connector CNB2 foreffecting signal transmission between the flash device and a controlcircuit FCC so as to control the flash device.

Reference character LMC represents a light measuring circuit. The resultof the light measuring as effected by light measuring circuit LMC isapplied to an analog input terminal ANI of the microcomputer. Themicrocomputer also receives a reference potential for thedigital-to-analog conversion to its terminal VR1. Reference characterDPC represents a display circuit operable to drive both a liquid crystaldisplay section LDP for the data display and a light emitting diode FLDfor the display of flash photography. Display circuit DPC receivesdisplay data produced from a terminal SOU during a period in which theoutput of a terminal O10 is "High" and effects the display based on thisdata. The details of the display section will be described later inconnection with FIG. 12. Reference character RLC represents a releasecircuit which releases the engagement of an exposure control mechanismbased on a pulse from a terminal O12.

Reference character APC represents an aperture control circuit operableto read data of the number of f-stop positions to be stopped down, whichare fed from terminal SOU during a period in which a terminal O13 is"High", and to interrupt the stop-down of the aperture of the camera todetermine the aperture opening when the data so read coincide with thenumber of f-stop positions actually stopped down. Reference characterTIC represents an exposure time control circuit operable to readexposure time control data outputed from terminal SOU during a period inwhich a terminal O14 is "High" and to initiate a shutter closingoperation after a time corresponding to the data so read has passedsince the closure of the count switch S3. Furthermore, a terminal TIEbecomes "High" when a release signal RLS is outputed, and becomes "Low"after a predetermined time, for example, 50 millisecond, has passedsubsequent to the initiation of the shutter closing operation.

With reference to the flow chart shown in FIG. 7, the operation of thissystem will now be described. When the power supply is initiated from aterminal VC, the microcomputer MCB is fed with the electric power andperforms an initial resetting operation. In addition, by the power-onreset signal PR1, the flip-flop RF1 is reset and the display circuit DPCfed with the electric power from terminal VC is also reset.

Microcomputer MCB produces "High" from terminals O1 to O4 and "Low" fromterminals O5 to O18 at step #0. In addition, it produces "High" fromterminal O31 and "Low" from terminals O30 and O32 to perform the serialinput and output operation. Thereupon, the data on the film cartridgefrom detector CAD are read in register IOR through circuit CIM which arein turn set in a register CAR. The method of setting the data inregister CAR is shown in Table 3.

Subsequently, when microcomputer MCB produces "High" from its outputterminal O32, the serial input and output reading is performed, therebyserially reading the ISO data stored in a register LAC. The ISO data soread out are then set in a register MER. Then, a decision is made inorder to determine if input terminal i20 is "High". If it is "High", itmeans that the output voltage of the back-up battery BUB is sufficient.Then, a further decision is made to determine if the data read out fromthe register LAC are normal. This decision is such that, unless all ofthe bits are "0", the data so read out are determined normal. Thus, ifthe back-up battery is normal and the data from the register LAC arenormal, data MER read out from the register LAC are set in a registerSVR and interruption to terminals itA and itB is enabled with theprogram flow proceeding to step #3.

On the contrary, if the output voltage of the back-up battery BUB isdetermined lower than the predetermined value at step #1, or if theresult of determination at step #2 indicates that the normal data arenot read out from the register LAC, the program flow proceeds to step#4. At step #4, a decision is made in order to determine, by examiningthe content of register CAR, whether the data from the film cartridgeare read in. If the result of the determination is yes, the ISO databased on the data from the film cartridge are set in the register SVR,and if it is no, fixed data (for example, ISO 100 Sv=5) are set in theregister SVR. Then, the content of the register SVR are set in aninput/output register IOR. Then, terminal O30 produces "High" and,thereafter, the serial input and output reading is performed. Thus, thecontents of the register SVR are transferred to a storage register LAC.Subsequently, bits MDR0 and MDR7 are set to be "1" and the remainingbits are set to be "0". Register MDR is the register in which dataindicative of display methods are set, the weight of each bit being asfollows.

A bit MDR0 is "0" when neither a symbol of ISO nor a symbol of SS isdisplayed, but becomes "1" when the symbol of ISO or SS is displayed.MDR1 is "1" when the exposure time is to be displayed at the displaysection, but becomes "0" when the ISO data is displayed. MDR2 and MDR3are "0" and "10" if override data are on a "+side" and a "-side",respectively, when the override data is to be displayed. When theoverride data is 0 and are to be displayed, MDR2 and MDR3 become "11".But, they become "00" when no override data is displayed. Accordingly,when MDR2 and MDR3 are "00", no display concerning the override iseffected. When they are "01", a symbol "+/-" of the override isdisplayed together with "+" preceding the override data; when they are"01", the symbol "+/-" is displayed together with "-" preceding theoverride data; and when they are "11", the symbol "+/-" is displayedand, at this time, the displayed override data, which is 0, is appliedwith neither "+" nor "-" preceding such a display "0". It is to be notedthat, if MDR2 and MDR3 are "01" and "10", the symbol "+ /-" will bedisplayed even when an exposure control value is displayed.

MDR4 is "1" when an F-value is to be displayed and when "0" it is notdisplayed. Accordingly, when it is "1", "F" is displayed, but when it is"0", "F" is not displayed. MDR5 and MDR6 are set with a symbolrepresentative of a display manner of the light emitting diode FLD whichindicates the state of the flash device. When it is "00", the flashdevice is not mounted on the camera and the light emitting diode is notlit. When it is "01", it indicates that the flash device is mounted onthe camera body and is powered with the electric power and the blinkingtakes place at the frequency of 2Hz. When it is "10", it indicates thatthe charging of the flash device has completed with the light emittingdiode being lit. When it is "11", it indicates the completion of thelight adjustment and, in this case, the light emitting diode FLD blinksat the frequency of 8Hz. MDR7 permits the entire liquid crystal displayunit to blink at 2Hz when it is "1", but it is lit continuously when itis "0".

Then, the contents of the register SVR, blank display data BLD, thecontents of the register MDR are transferred to the display section DPCand, at the same time, the terminals O1, O2 and O4 produce "Low" toenable the interruption to the terminals itA and itB, and ten seconds iswaited for. Accordingly, when the contents of the storage circuit LACpowered by the back-up battery BUB vanish or when the output of theback-up battery BUB is not normal on the occasion when the power sourcebattery BAB for the microcomputer is loaded, the ISO data based on thedata on the film cartridge or the fixed ISO data is set, and these dataare displayed blinking for ten seconds for the warning. Moreover, sincethe terminals O2 and O4 are producing "Low", an interruption signal canbe applied to terminal itA only when the OSI switch ISS is closed.Accordingly, no exposure control operation is initiated even when therelease button is manipulated. In other words, the shutter mechanism isheld in a release-locked condition. In order to escape from thiscondition, the ISO switch should be manipulated or ten seconds should bewaited for.

After the passage of ten seconds, the terminals O2 and O4 are produce"High" and terminal O1 produces "Low" at step #3, and thereafter, datanecessary to turn of the display are fed to the display section DPC anda "HALT" condition is then resumed. However, it is to be noted that,when the normal ISO data is read out from the register LAC, this data isset and the program flow immediately proceeds to step #3 with no displayconsequently taking place.

FIG. 8 illustrate the operation that takes place when the interruptionsignal is inputed to terminal itB as a result of the closure of the backcover. At first, a predetermined time (for example, 0.5 sec.) is waitedafter the closure of the back cover. This is because, shortly after theback cover has been closed, the film cartridge may undergo a vibratorymotion and, therefore, the contact of the feelers 15 and 16 with thefilm cartridge may not be stabilized. Then, terminals O2, O3 and O4produce "High" and terminals O1, O5 to O18, O30 and O32 produce "Low".Furthermore, terminal O31 produces "High", and then the serial input andoutput reading is performed. Accordingly, data are read out from thefilm cartridge. Subsequently, based on the read data, a decision is madein order to determine if the data is provided on the film cartridge. Ifthe data are provided on the film cartridge, the ISO data based on thisdata is set in the register SVR, but if it is not provided, the contentsof the register SVR remain unchanged.

Thereafter, by rendering the bit MDR0 to be "1" and the remaining bitsMDR1 to MDR7 to be "0", the contents of the register SVR, the blank dataBLD and the contents of the register MDR are transferred to the displaysection DPC, thereby displaying the set ISO data. Then, terminal O18produces a pulse with which the flip-flop RF1 is reset. Then, terminalsitA and itB are enabled to receive interruption signals within the nextfive seconds. After the lapse of the five seconds, the display is turnedoff with the "HALT" condition established in a manner similar to thateffected at step #3.

The details of detection of the presence of CAR at steps #4 or #8 willnow be described with reference to FIG. 9. As shown in Table 1, in thecase of the film cartridge provided with the code pattern, at least oneof the portions K6 and K5 is a conductive portion. If "1" is read ineither one of the bits CAR4 and CAR3 of the register CAR, the filmcartridge loaded is regarded as having the code pattern, and therefore,the setting of the data from the code pattern is carried out. On theother hand, if both of the bits are "0", it means that the filmcartridge having no code pattern is loaded or that no film cartridge isloaded and, in that case, no setting of the data based on the contentsof the register is carried out.

The details of the film sensitivity setting operation at steps #7 or #10will be hereinafter described in connection with FIG. 10. At first, 16His set in the register SVR, wherein H represents a hexademical numbersystem.

Each of the registers SVR1 and SVR2 has 8 bits, each bit being weighted16, 8, 4, 2, 1, 1/2, 1/4 and 1/8 from the most significant bit. The filmsensitivity is variable by a unit of 1/3 Ev in terms of APEX value. If afraction portion of the film sensitivity of the film loaded in thecamera is 1/3 or 2/3, it is approximated to 1/4 or 3/4 (=1/4+1/2),respectively. Accordingly, 16H set in the register SVR at step #1corresponds to Sv=22.

Then, if bits CAR4 and CAR5 of the register CAR are "11", 08H, is addedto the contents of the register SVR1. Similarly, if CAR4 and CAR5 are"10", o4H is added, and if they are "01", 02H is added. Accordingly, ifthe bits of the fraction portion are "11", Sv=1 is added to give 1EHwith the fraction portion being 3/4. On the other hand, if the bits ofthe fraction portion are "10", Sv=1/2 is added to give 1AH with thefraction portion being 1/4. Furthermore, if the bits are "01", Sv=1/4 isadded to give 18H with the fraction portion being 0.

Subsequently, if the bit CAR2 of the register CAR is 1, Sv=4 is added tothe contents of the register SVR1. Similarly, if the bit CAR1 of theregister CAR is 1, Sv=2 is added, and if the bit CAR0 is 1, Sv=1 isadded.

The foregoing operation will now be described in connection with thecase in which the film cartridge of ISO400 is loaded in the camera. Inthis case, as shown in Table 1, the portions K4 and K5 are conductive.In the register CAR, the bits CAR3 and CAR2 are "1" while the bits CAR4,CAR1 and CAR0 are "0". Then, 22H is added to the register SVR to give38H. This data will become 4+2+1=7 according to the weighting system ofeach bit, which corresponds to the APEX value Sv=7 at ISO400.

The operation of the circuit shown in FIG. 4 will now be described inconnection with the flow charts of FIGS. 11a to 11-h. When one of lightmeasuring switch S1, ISO switch ISS, and override switch ORS is closed,provided that the power source battery BAB is loaded with the mainswitch BMS being closed, the interruption signal is applied to terminalitA through the AND circuit AN3 to initiate the operation starting fromstep #1. At first, a decision is made in order to determine if thecontent of a flag CCF is "1". This flag CCF will carry "1" when the datafor the exposure control is calculated, or will carry "0" when it is notcalculated. The operation which will take place when the interruptionsignal is inputed to terminal itA while the exposure control value hasbeen calculated will be described later.

When the flag CCF is "0", terminal O1 produces "High". Thereupon, atransistor BTO is brought in a conductive state, thereby supplyingelectric power from the line VB. In addition, the AND circuit AN1 isdisabled, and the AND circuit AN2 is enabled. Accordingly, a signal fromthe release switch S2 can be applied to terminal itA as an interruptionsignal. Then, terminals O3 and O4 produce "Low", and terminal O2produces "High", thereby detecting whether terminal i1 is producing"High" or not. If terminal i1 is producing "High", interruption takesplace as a result of the closure of the light measuring switch S1 and aflag LMF is therefore set to "1" and, at the same time, terminal O2produces "Low". If the switch S1 is held open, and if it is detected atstep #13 that terminal i1 is "Low", only terminal O3 produces "High".Then, it is detected whether or not terminal i1 is "High". If it isdetected as "High", meaning that the interruption has taken place as aresult of the closure of the ISO switch ISS, a flag ISF is set with "1".However, if terminal i1 is "Low", meaning that the interruption hastaken place as a result of the closure of the override switch ORS, aflag ORF is set with "1".

Thereafter, terminal O3 produces "Low" with the program proceeding tostep #14.

At step #14, terminal O5 produces "High". Then, by repeating the serialinput and output operation for a predetermined number of times, the datafrom the lens assembly LE are read in and the data so read in aresequentially stored in the register LDR. After this operation, terminalO5 produces "Low" and terminal O31 and P32 produce "High". Thereafter,the serial input and output reading is performed to transfer the modesignal, applied from the code plate EM, and the signal from the counterswitch SFC to register MOR. Thereafter, the terminals O31 and O32produce "Low". It is to be noted that the data representing the mode isset in the bits MOR0 and MOR1 while the signal from the counter switchSFC is set in the bit MOR2. In this way, both the condition of the filmcounter and a signal indicative of the exposure control mode are storedin the register MOR.

Next, when terminal O9 produces "High", a pulse having a pulse width of50 microsecond is outputed from terminal O8. Then, when data "00H" hasbeen set in the input/output register IOR, the serial input and outputoperation is performed. Upon this operation, the data from the flashdevice FL is loaded in the register IOR, which is in turn stored in theregister FDR. Step #15 is performed after terminal 09 produces "Low".

At step #15, a signal obtained from the light measuring circuit LMC,indicating the result of measurement of a target object to bephotographed, is subjected to the analog-to-digital conversion.Thereafter, in order to eliminate, on the basis of the data from thelens assembly LE, terms of the full aperture value Avo and the fullaperture metering error Avc both included in the analog-to-digitalconverted data, the equation

    Bv-Avo-Avc)+Avo+Avc=Bv

is calculated to give a data of the brightness of the target object.Thereupon, the following equation

    Bv+(SVR)=Ev

is calculated to given the exposure value Ev.

Then, a decision is made as to determine if the bits MDR2 and MDR3 ofthe register MDR are "01". If they are "01", it means of the override onthe "+" side as hereinbefore described and, therefore, the contents of aregister ORR1 in which the override data on the "+" side is set issubtracted from the exposure value Ev to give an Ev value. On the otherhand, if the contents of MDR2 and MDR3 are not "01", a decision issubsequently made of the override on the "-" side and, therefore, thecontents of a register ORR2 in which the override data on the "-" sideis added to the exposure value Ev to give an Ev value.

Upon completion of the foregoing operation, the program flow proceeds tostep #16 at which a calculating operation of the exposure control datatakes place. At first, at step #16, a decision is made in order todetermine if the P mode has been established. If the P mode has beenestablished, a calculation for the photo-taking under the P mode withthe use of an ambient light and a calculation for the photo-taking underthe P mode with the use of a flash light are performed, and a flag DCF1is set to "0", followed by step #18. The flag DCF1 is a flag which willcarry "1", when the present aperture value or the present exposure timeis changed, but will carry "0"when none of these is changed. Under the Pmode, since any change of the aperture value or the exposure time willnot be accepted, the flag DCF1 is always "0".

If the result of decision at step #16 indicates that it is not the Pmode, the program flow proceeds to step #19 at which another decision ismade to find if it is the A mode. If it shows that it is the A mode, achange in the present aperture value is accepted and for this purpose,the operation is performed to effect such change of the data. At first,terminal O2 produces "High" and a decision is then made to find ifterminal i2 is "High". If terminal i2 is "High", the aperture settingswitch FSS is to be closed. Then, a decision is made to find if terminali3 is "High". If terminal i3 is "High", the up-shift switch UPS is to beclosed. In this case, terminal O2 produces "Low", and the operation isperformed to change the data in a direction towards a smaller aperture.That is, a decision is first made to find if the contents of a registerAVR3 in which the preset aperture value data is set is on the side of alarger aperture than the full aperture value data Avo fed from the ROMof the lens assembly LE. If the result of decision is yes (which occurswhen the lens assembly is interchanged), the contents of the registerAVR3 is set to Avo with the program flow subsequently proceeding to step#20. On the other hand, if the result of the decision is no, that is, ifthe contents of the register AVR3 is not on the side of a largeraperture than Avo, another decision is made to find if it is equal toAvo. A data dAv from the lens assembly LE, if the contents of registerAVR3 is equal to Avo, or 1/2 if it is not equal thereto, is added to thecontents of the register AVR3 and a decision is then made to find if thecontents of the register is of a value greater than the maximum aperturevalue data Avm from the lens assembly. If it is of a greater value, themaximum aperture value Avm is set in the register AVR3 and the programflow proceeds to step #20, but if it is not of a greater value, step #20immediately takes place. The maximum aperture value data Avm is also fedfrom the lens ROM.

The data dAv will now be described. The full aperture value Avo takes adifferent value when the type of the interchangeable lens assembly ischanged. Some interchangeable lens assemblies ahve the full aperturevalue Avo which can be divided by 0.5Ev, i.e., in a unit of 0.5 Ev(Avo=0.5, 0.1, 1.5 2.0 . . .), and others not in a unit of 0.5 Ev (forexample, F2.5(Av=2.64), F3.5(Av=3.61), F1.8(Av=1.7) and so on). In thecamera body, however, the aperture value to be set is in the multiple of0.5 Ev, except for the fully opened aperture value. Therefore, in thecase where the fully opened aperture is not in the multiple of 0.5 Ev,the first stop-down change from the fully opened aperture value to thenext aperture value results in a change dAv which is smaller than 0.5Ev. Therefore, after the first stop-down change, the aperture value canbe set to the multiple of 0.5 Ev, with the aperture change effected atthe rate of 0.5 Ev. Accordingly, in the case of the F2.5 lens assembly,dAv=0.36; in the case of the F3.5 lens assembly, dAv=0.39; and in thecase of the F1.8 lens assembly, dAv=0.3. This data dAv is alsotransferred to the camera body from the lens ROM.

If it is determined that terminal i3 is not "High" and, at the sametime, the up-shift switch UPS is not closed at the timing when terminalO2 is "High", terminal O2 produces "Low", and terminal O3 produces"High", thereby making a detection, based on the state of terminal i3,whether or not the down-shift switch is closed. If the down-shift switchDOS is closed, terminal O3 produces "Low" and 1/2 is subtracted from thecontent of the register AVR3. Then, a decision is made to find if theresult of the subtraction is on the side of the fully opened aperturewith respect to the fully opened aperture value Avo, if it is of a valueon the side of the fully opened aperture, the fully opened aperturevalue Avo is set in the register AVR3 with the program flow subsequentlyproceeding to step #20.

At step #20, the flag DCF1 is set to "1" to show that the setting datahas been changed, followed by step #21. On the other hand, in the casewhere the aperture switch FSS is not closed, or where both the up-shiftand down-shift switches UPS and DOS are not closed, the data will not bechanged and the flag DCF1 is set to "0" at step #23, followed by step#21. At step #21, the calculation for the photo-taking under the A modewith the use of the ambient light is performed and, at the subsequentstep #22, the calculation for the photo-taking under the A mode with theuse of the flash light is performed. Thereafter, the program flowproceeds to step #24.

If it is determined that the mode is other than the A mode at step #19,a decision is made at step #25 to determine if it is the S mode. If itis determined as the S mode, a decision is made at steps #25 and #26 todetermine from the state of terminal i2 if the exposure time switch SSSis closed. If the result shows that the exposure time switch SSS is notclosed, the flag DCF1 is set to "0" at step #28 followed by step #29. Onthe other hand, if the result of decision at step #27 shows that theexposure time switch SSS is closed, a decision is then made to find ifthe up-shift switch UPS is closed. If the result of decision at step #30shows that the up-shift switch UPS is closed, "1" is added to thecontent of the register TVR3 in which the present exposure time data isset. Whether or not the result of the addition is greater than the dataTvm is determined at step #31. If the result of the addition is greaterthan the data Tvm, Tvm is set in the register TVR3, but if it is notgreater than that, the content remains unchanged and the flag DCF1 isset to "1" at step #32, followed by step #29.

If the result of the decision at step #30 shows that the up-shift switchUPS is not closed, whether or not the down-shift switch DOS is closed isdetermined at step #33. If the down-shift switch DOS is closed, "1" issubstracted from the register TVR3 at step #34, and subsequently, adecision is made to determine if the result of the subtraction has alonger exposure time than the maximum exposure time Tvo. If it has thelonger exposure time, Tvo is set in the register TVR3, but if not, thecontent remains unchanged and the flag DCF1 is set to "1". The programflow then proceeding to step #29.

When the exposure time switch SSS is not closed, or when both of theup-shift and the down-shift switches UPS and DOS are closed while theexposure time switch SSS is closed, the flag DCF1 is set to "0" and theprogram flow proceeds to step #29. At step #29, the calculation for thephoto-taking under the S mode with the use of the ambient light isperformed, followed by the calculation for the photo-taking under the Smode with the use of the flash light. Then, the program flowsubsequently proceeds to step #18.

If it is determined at step #25 that the mode is not the S mode, themode is the M mode. In that case, both the aperture value data and theexposure time value data can be changed. When both of the aperture valuedata and the exposure time data have been changed in a manner similar tothat described hereinbefore, the calculation for the photo-taking underthe M mode with the use of the ambient light and that with the use ofthe flash light are successively performed. Thereafter, the program flowproceeds to step #18.

At step #18, since the exposure control data has been calculated, theexposure control operation can be carried out and thus, flag CCF is setto "1". Then, the interruption signal can be inputed to terminal itA oritB at any time. Subsequently, a decision is made based on the data fromthe flash device FL in order to find if the flash device being poweredis loaded. If no loading signal is present, indicating that the flashdevice is not loaded, the bits MDR5 and MDR6 of the register MDR arerendered to be "00", and the program flow proceeds to step #35. If,however, the loading signal is present, a decision is then made to findif a signal indicative of the completion of the light adjustment, whichsignal is hereinafter referred to as FDC signal, is being inputed. Ifthe FDC signal is inputed, the bits MDR5 and MDR6 of the register MDRare set to "11" with the program flow then proceeding to step #35. Onthe other hand, if the FCD signal is not inputed, a decision is thenmade to determine if a charge completion signal is being inputed. If thecharge completion signal is inputed, bits MDR5 and MDR6 are set to "10",but if not, they are set to "01".

At step #35, terminal O9 produces "High" and, thereafter, the transferof data from the camera to the flash device FL takes place. At thesubsequent step #36, a pulse having a pulse width of 100 microsecond isproduced from terminal O8. Then, the ISO data set in the register SVR isset in the input/output register IOR, the content of which is outputedthrough a digital-to-analog converter from an analog signal outputterminal AN0. Thereupon, by performing the serial input and outputoperation, the ISO data is transferred to the flash device. Followingthat, the content of the register AVR2 in which the aperture value datafor the flash photography is loaded is loaded in the register IOR and isthen transferred to the flash device and, at the same time, the contentof the register TVR2 in which the exposure time data for the flashphotography is set is set in the register IOR and is then transferred tothe flash device. Thereafter, of the data from the lens assembly LE, thecontent of a register LDRf in which a focal length data is set is loadedin the register IOR and is then transferred to the flash device FL,thereby producing "Low" from terminal O9. In this way, the data from thecamera body are transmitted to the flash device. Based on these data sotransferred, the flash device performs various functions including thedisplay of the available range and the automatic setting of the lightingcoverage angle.

At step #40, a decision is made as to whether the flag ISF is "1". Whenit is "1" meaning that the ISO switch is closed, the program goes tostep #43. On the other hand, when it is "0", a decision is made at step#41 in order to determine if the flag ORF is "1". If it is "1",indicating the closure of the override switch ORS, the program flowproceeds to step #44. On the other hand, if it is "0", the content of abit MOR2 of register MOR is discriminated. If the content of the bitMOR2 is "0", it indicates that the film count switch SFC is closed, butthe film counter has not yet reached the position 1 (the first framenumber that can be photographed) and, therefore, the program flowproceeds to step #52. If at step #42, it is determined that bit MOR2 ofregister MOR is "1" meaning that the film counter switch SFC is opened,the program flow proceeds to step #46. At this time, since it is underthe mode in which the exposure control value is to be displayed, bitsMDR2 and MDR3 are rendered to be "00" if they are "11", and at the sametime, bits MDR1 and MDR4 are rendered to be "1". Accordingly, the symbol"+/-" will not be displayed unless the override takes place, and symbolsF and SS are displayed on the display device LDP.

Next, a decision is made to find whether the charge completion signal isbeing inputed. If the charge completion signal is inputed from the flashdevice FL to the microcomputer MCB, both the exposure time (content ofthe register TVR2) and the aperture value (content of the register AVR2)for the flash photography are serially transferred to the displaysection DPC, but if it is not inputed, both the exposure time (contentof the register TVR1) and the aperture value (content of the registerAVR1) for the photography under the ambient light are seriallytransferred to the display section DPC. Thereafter, the program flowproceeds to step #49 shown in FIG. 11e.

If it is determined at step #40 that the ISD switch ISS is closed, step#43 takes place at which "High" is produced from terminal O2. At step#50, a decision is made in order to determine whether the up-shiftswitch UPS is closed or not. When the up-shift switch UPS is closed, adecision is further made at the subsequent step #58 in order todetermine if a fraction of the ISD data is 1/4. If it is 1/4, 1/2 isadded to 1/4 and the result is placed in the register SVR. But, if it isnot 1/4, 1/4 is added to that data and the result is placed in theregister SVR. Accordingly, the fraction portion becomes 1/4 if it is 0,3/4 if it is 1/4, or 0 if it is 3/4. That is, as hereinbefore described,such compromises as 1/3=1/4, 2/3=3/4 and 0=0 are employed. Then, adecision is made in order to find whether or not the content of theregister SVR2 is greater than the maximum ISO data Svm. If the contentof the register SVR2 is greater than Svm, Svm is set in the registerSVR2, but if it is not, Svm remain unchanged. Thereafter, the programflow proceeds to step #52.

When, at step #50, it is determined that the up-shift switch UPS is notclosed, step #50 is proceeds to steps #53 and #54 at which only terminalO3 is "High". At the subsequent step #55, a decision is made in order tofind whether or not the down-shift switch DOS is closed. When thedown-shift switch DOS is closed, and if a fraction portion of themanually present data is 3/4, 1/2 is subtracted, but when it is not 3/4,1/4 is subtracted. In other words, it is assumed as 1/4 if the fractionportion is 3/4, 0 if it is 1/4, or 3/4 if it is 0. Then, a decision ismade in order to determine if the content of the register SVR is smallerthan the minimum ISO data Svo. If the content of the register SVR issmaller than the data Svo, the data Svo is set in the register SVR2, butif it is not, the content of the register SVR remains unchanged.Thereafter, the program flow proceeds to step #52.

In addition, if the result of the decision at step #55 shows that thedown-shift switch DOS is not closed, the content of the register SVRremain unchanged and the program flow proceeds to step #52.

At step #52, flag DCF2 is set to "1", and at the same time, bit MDR0 isset to "1" and bits MDR1, MDR4 and MDR7 are set to be "0". Then, thecontents of the register SVR are loaded in the register IOR, and "High"is produced from terminal O30, thereby carrying out the serial input andoutput operation. Thereupon, a newly presented ISO data is fixedlystored in the storage-register LAC (FIG. 5) within the circuit CIM.Subsequently, data necessary to turn off the display section and the ISOdata are fed to the display circuit DPC and the program flow thenproceeds to step #49.

If at step #41 it is determined that the flag ORF is "1" and theoverride switch ORS is closed, step #44 takes place. That is, at step#57, a decision is made in order to find whether or not the up-shiftswitch UPS is closed. If the up-shift switch UPS is closed, bits MDR2and MDR3 produce "01", and 1/2 is added to the content of the registerORR1. Then, another decision is made in order to determine whether ornot the content of the register ORR1 is above the maximum value ODm. Ifit is above the maximum value ODm, ODm is set in the register ORR1, butif it is not, the content of the register ORR1 is unchanged and theprogram flow proceeds to step #58 at which the flag DCF is set to "1".Then, the program proceeds to step #60.

If at step #57 it is determined that the up-shift switch UPS is notclosed, step #61 takes place to produce "High" from only terminal O3.Then, the program proceeds to step #62 at which a decision is made inorder to determine if the down-shift switch DOS is closed. If thedown-shift switch DOS is closed, 1/2 is added to the content of theregister ORR2 and, if the result exceeds the maximum value ODm, themaximum value ODm is set in the register ORR2, but if it does notexceeds, the content remains unchanged and the flag DCF2 is set to "1 ".Then, the program proceeds to step #60.

If at step #62 with down-shift switch DOS is not closed, the flag DCF2is set to "1" without altering MDR2, MDR3 and the registers ORR1 andORR2, and thereafter, the program goes to step #60 shown in FIG. 11f. Atstep #60, a decision is made in order to determine if the bits MDR2 andMDR3 of the register MDR are "00". If they are "00", they are changed to"11" for the display. Then, MDR0, MDR1, MDR4, MDR7 are made to be "0".Accordingly, in such case, only the symbol "+/-" for the override isdisplayed.

Then, the blank data BLD is outputed to the register IOR and thentransferred to the display section DPC to turn off the display of digitsindicative of the ISO or SS value. Thereafter, if the contents of MDR2and MDR3 are "01" indicating that the override is effected on the "+"side, the content of the register ORR1 is transferred to the displaysection DPC, but if they are not "01", the content of the register ORR2is transferred to the display section DPC. Then, the program goes tostep #49. At step #49, the content of the register MDR is transferred tothe display section DPC. Then, the terminal 011 produces "High", therebyenabling the display by the light emitting diode FLD in the displaysection.

Subsequently, a decision is made to determine if either one of the flagsDCF1 and DCF2 is "1". If either one is "1", it indicates that the datahas been changed. In that case, in order to prevent the data from beingchanged at a high speed, a predetermined time is waited, and then theprogram proceeds to step #65. On the other hand, if both of the flagsDCF1 and DCF2 are "0", step #65 is carried out immediately. At step #65,the terminals O2, O3 and O4 produce "High". Then, it is detected whetheror not the terminals i1, i2 or i3 is receiving "High", that is, whetheror not at least one of the key switches is closed, is determined. If anyone of the key switch is closed, a data representing five seconds is setin an internal counter ICO. Then a decision is made as to determine ifthe main switch BMS is closed. If the main switch BMS is closed, theterminals O2 and O4 produce "Low" and a decision is then made todetermine if the switch ISS has been closed. If the switch ISS isclosed, the flag ISF is set to "1", and at the same time, the flags ORFand LMF are set to "0 ". Then, the program returns to step #41. However,if the switch ISS has not yet been closed, a decision is further made asto determine if the switch ORS is closed. When it is determined that theswitch ORS is closed, the flag ORF is set to "1", and at the same time,the flags LMF and ISF are set to "0". Then, the program returns to step#14. Where both of the switch ISS and ORS are opened, the flag LMF isset to "1 " and the program flow then returns to step #14. Accordingly,during a period of five seconds in which none of the switches is closed,the exposure time and the aperture values are displayed.

If none of the key switches is closed, a decision is made as todetermine if the content of the internal counter ICO is "0". If it is"0", the program flow proceeds to step #67, but if it is not "0", adecision is then further made as to find if the reset switch S4 isclosed. If the reset switch S4 is not closed, the state of the mainswitch BMS is discriminated. The the program then returns from step #66to step #14.

After the lapse of five seconds subsequent to the opening of all of thekey switches, or at the moment when the reset switch S4 is closed orwhen the main switch BMS is opened, the program goes to step #67,thereby producing "LOW" from the terminals O1 and O5 to O18, and alsothen, the flags CCF, LMF, ISF and ORF are set to "0", and in turn theinterruption by means of the terminal itA or itB is enabled. And theflow advances to turn off the display in a manner similar to theoperation at step #3 et seqq. Then, the "HALT" condition is established.

When the release switch S2 is closed while the calculation of theexposure control value has been completed to set "1" in the flag CCF,interruption to terminal itA is accepted, and thereafter, the programproceeds to step #70. At step #70, terminal O9 produces "High" and thepulse of 50 microsecond in duration is outputed from terminal O8 topermit the data to read from the flash device. A decision is then madeto determine if the charge completion signal is inputed. If it isinputed, the content of a register PVR2 in which the value of the numberof f-stop positions to be stopped down for the flash photography is set,is transferred to the aperture control circuit APC. But if it is notinputed, the content of a register PVR1 in which the value of the numberof f-stop positions to be stopped down for the photography under theambient light is set, is transferred to the aperture control circuitAPC. Thereafter, a decision is made to determine again if the chargecompletion signal is inputed. If it is inputed, the content of theregister TVR2 in which the exposure time for the flash photography isset, is transferred to the exposure time control circuit TIC. But if itis not inputed, the content of the register TVR1 in which the exposuretime for the photography under the ambient light is set, is transferredto the exposure time control circuit TIC.

Then, when the terminal O9 produces "High", a pulse of 50 microsecond induration is transmitted from the terminal O8 to the flash device FL.Accordingly, the flash device can detect that the exposure controloperation has been initiated. Thereupon, terminal O11 produces "Low" toturn off the light emitting diod FLD so that no lighting display willtake place during the exposure control being taken place. Subsequently,a pulse is outputed from terminal 012 to cause the release circuit RLCto effect a shutter release operation thereby to initiate the exposurecontrol operation. Then, it is waited until the reset switch S4 closesin response to the completion of opening of the shutter curtain, whichis effected after the completion of the exposure control operation. Whenthe reset switch S4 is so closed, the terminals O2 to O4 produce "High".Then, the program returns to step #67, thereby to repeat the previouslydescribed operation before the "HALT" condition is established.

FIG. 12 illustrates the details of the display circuit shown in FIG. 4.In this circuit, when a terminal CDP becomes "High", a latch pulse isoutputed from a latch control circuit LAC to terminals LN1, LN2 and LN3each time eight synchronizing clock pulses SCP are inputed. The dataread in the serial input register SIR are sequentially taken inregisters REG1, REG2 and REG3. Accordingly, the exposure time or the ISOvalue data is stored in the register REG1, the aperture value or theoverride value data is stored in the register REG2, and the display modedata (that is, the content of the internal register MDR of themicrocomputer MCB) is stored in the register REG 3. Here, the outputs ofterminals e0 to e7 corresponding to the bits MDR0 to MDR7 of theregister MDR.

A decoder DE1 serves to convert the output of the register REF1 into avalue for the display of the exposure time, and a decoder DE2 serves toconvert into a value for the display of the ISO data. A data selectorDS1 serves to send data from the decoder DE1 if terminal e1 is "High",that is, during the exposure time display mode, and to send data fromthe decoder DE2 if terminal e1 is "Low", that is, during the ISO displaymode. In addition thereto, a decoder DE3 serves to convert the output ofthe register REG3 into a value for the display of the aperture value,and a decoder DE4 serves to convert into a value for the display of theoverride. Another data selector DS2 serves to send data from the decoderDE3 if terminal e4 is "High", that is, during the aperture value displaymode, but it serves to send data from the decoder DE4 if terminal e4 is"Low", that is, when the mode is not the aperture value display mode. Afurther decoder DE5 is a decoder operable to convert into data for thedisplay of the symbol, based on data from the terminals e0 to e4 of theregister REG3.

A timing signal output circuit TIC serves to output clock pulses of 8Hzfrom a terminal j1 and clock pulses of 2Hz from a terminal j2 and alsoto supply a timing signal both to a common signal output circuit COD anda segment signal output circuit SED. The segment signal output circuitSED serves to output a signal for the display, based on the data fedfrom the data selectors DS1 and DS2 and the decoder DE5, to activate aliquid crystal display. If terminal e7 of the register REG3 is "High",2Hz clock pulses emerge from an AND circuit G1 to cause the liquidcrystal display to blink at 2Hz.

Both signals from the terminals e5 and e6 of the register REG3 and the8Hz and 2Hz clock pulses from the respective terminals j1 and j2 aresupplied to a drive circuit LDC. If a terminal DPE is "High", circuitLDC produces a drive signal to terminal FLD depending on the state ofthe flash device.

FIG. 13 illustrates a flow chart which is a modification of the flowchart shown in FIG. 7. The program flow to step #4 shown in FIG. 13 isthe same as in FIG. 7 except that a predetermined time is allowed topass before the data are completely read out from the film cartridge,and that both the exposure control data and the signal from the filmcounter switch are set in the read-out register MOR. The reason for thepassage of the predetermined time allowed before the data are completelyread out from the film cartridge is because, when the battery is loaded,vibration takes place to such an extent as to result in that the contactof the feelers with the film cartridge may not be stabilized and,therefore, there is the possibility that, if the data are read out fromthe film cartridge immediately after the loading of the battery, theywould be read out erroneously. The predetermined time allowed to passsubsequent to the loading of the battery is so selected for the contactof the feelers with the film cartridge to be stabilized before the dataare actually read out from the film cartridge. When it is determined atstep #4 that the data has been read in from the film cartridge, the dataso read out is set in the register SVR at step #7 and a program flowsimilar to that occurring when the back-up battery BUB is normal and theoutput of the register LAC is also normal is subsequently performed.This will not constitute an exposure error even if the ISO data are readin from the film cartridge at the time of the replacement of thebattery, and neither the blinker display warning of the ISO data nor therelease lock takes place.

On the other hand, if it is determined at step #4 that no data is readin from the film cartridge, the fixed ISO data (ISO 100 Svn) is set inthe register SVR at step #80 and this data is displayed by blinking forten seconds. If at this time two bits of the register MOR indicates thatthe counter switch CFS has not been closed, this ten seconds is utilizedas a period in which no drive is effected by any switch other than theISO switch ISS. Where the counter switch CFS is opened, since thepossibility is small that the film is loaded, only the blinking of ISOis effected and no drive is effected even by S1 and ORS. Unless the ISOswitch ISS is closed, the microcomputer MCB, after the passage of tenseconds, proceeds to step #81 at which the ISO display is effected andthe condition is established wherein a drive can be effected by anyswitch, the microcomputer MCB being subsequently brought to a halt.

It is to be noted that, in the foregoing embodiment, switch SFC in FIG.4a may be alternatively switched by detecting whether or not the film isactually loaded in the camera, e.g., by detecting the loading of thefilm cartridge or detecting directly the existance of the film (forexample, at a film spool). In such a case the release lock can bedisabled by detecting by means of switch SFC that the film has not yetbeen loaded.

FIG. 14 illustrates an example of the display according to the preferredembodiment of the present invention, wherein FIG. 14a illustrates anexample of the display effected after the setting of the exposure timeand FIG. 14b illustrate an example of the display effected at the timeof the setting of the film sensitivity. As shown in FIG. 14a, the firstdisplay area which is used to display the shutter speed and the filmsensitivity one at a time is shown as displaying the shutter speedreading 1/2000 second, while a second display area is shown asdisplaying another data relating to exposure, e.g., the aperture valuereading F5.6. On the other hand, in FIG. 14b, the first display area isshown as displaying the film sensitivity reading ISO 400 while thesecond display area displays nothing. Thus, information to be displayedat the time of the setting of the shutter speed is enriched with anotherdata displayed as well as the shutter speed. On the other hand, at thetime of the setting of the film sensitivity which solely depends on anactually loaded particular film without any comparison with another dataand which has no necessity to be changed depending on each shot as longas the once loaded film is continued to be used, nothing is displayedother than the film sensitivity to clarigy such a nature of the filmspeed setting.

Although in the foregoing embodiment the data on the film cartridge areread out at a particular time after a lapse of a predetermined timeperiod from the closure of the back lid, the concept of the presentinvention can be equally applicable to a type of camera wherein, with nostorage for storing the read ISO information used therein, the ISO datais continuously read in at all times. In such a case, the reading of thedata from the film cartridge is inhibited until the predetermined timeperiod passes subsequent to the closure of the back lid.

In addition, although the switching of the exposure control modes hasbeen described as effected by means of the slide switch, it is to benoted that the same can be effected by a combination of a key forinstructing the change in the exposure control mode and one of theup-shift and down-shift keys. In such a case, it should be designedthat, even by a depression of the exposure control mode changeinstructing key, interruption can be effected to the interruptingterminal itA of the microcomputer to permit the light measurement anddisplay to be performed.

Moreover, although in the foregoing embodiment the back-up battery andthe storage circuit have been described as used for keeping the ISO datastored even when the main battery is removed for replacement purpose,they may not be always necessary. In the case of a camera without such aback-up means, the decision to make both the warning and the releaselock should be effected, depending on whether or not the data issuccessfully read from the film cartridge upon the loading of the newmain battery.

Although the present invention has been fully described with referenceto several preferred embodiments, many modifications and variationsthereof will now be apparent to those skilled in the art, and the scopeof the present invention is therefore to be limited not by the detailsof the preferred embodiments described above, but only by the terms ofappended claims.

                  TABLE 1                                                         ______________________________________                                        ISO        Sv     K2      K3  K4     K5  K6                                   ______________________________________                                        25         3      X       X   X      O   X                                    32         31/3   X       X   X      X   O                                    40         32/3   X       X   X      O   O                                    50         4      O       X   X      O   X                                    64         41/3   O       X   X      X   O                                    80         42/3   O       X   X      O   O                                    100        5      X       O   X      O   X                                    125        51/3   X       O   X      X   O                                    160        52/3   X       O   X      O   O                                    200        6      O       O   X      O   X                                    250        61/3   O       O   X      X   O                                    320        62/3   O       O   X      O   O                                    400        7      X       X   O      O   X                                    500        71/3   X       X   O      X   O                                    640        72/3   X       X   O      O   O                                    800        8      O       X   O      O   X                                    1000       81/3   O       X   O      X   O                                    1250       82/3   O       X   O      O   O                                    1600       9      X       O   O      O   X                                    2000       91/3   X       O   O      X   O                                    2500       92/3   X       O   O      O   O                                    3200       10     O       O   O      O   X                                    4000       101/3  O       O   O      X   O                                    5000       102/3  O       O   O      O   O                                                      .       .   .      .   .                                                      .       .   .      .   .                                                      .       .   .      .   .                                                      1       2   4      1/3 2/3                                  ______________________________________                                         O: Conductive                                                                 X: Nonconductive?                                                        

                  TABLE 2                                                         ______________________________________                                        Register Contents              Symbol                                         ______________________________________                                        TVR1     Exposure time for photo-taking                                                                      Tva                                            TVR2     Exposure time for flash photography                                                                 Tvf                                            TVR3     Preset Exposure time  Tvs                                            AVR1     Aperture value for photo-taking                                                                     Ava                                            AVR2     Aperture value for flash photography                                                                Avf                                            AVR3     Preset Aperture value Avs                                            ______________________________________                                    

                                      TABLE 3                                     __________________________________________________________________________    Bit  CAR7 CAR6                                                                              CAR5 CAR4                                                                              CAR3 CAR2                                                                              CAR1 CAR0                                     __________________________________________________________________________    Position  K12 K11  K6  K5   K4  K3   K2                                       Weight             2/3 1/3  4   2    1                                        __________________________________________________________________________

                  TABLE 4                                                         ______________________________________                                        Bit     Signal    Conditions                                                  ______________________________________                                        MDR0    0         No display of SS & ISO                                              1         Display SS or ISO                                           MDR1    0         Display ISO                                                         1         Display SS                                                  MDR2    01        Override on + side                                          MDR3    10        Override on - side                                                  11        Override 0                                                          00        No display of Override                                      MDR4    0         No display of F-stop                                                1         Display F-stop                                              MDR5    00        Light off indicating unloading                              MDR6    01        2 Hz blinking indicating loading                                    10        Light on indicating charge completion                               11        8 Hz blinking indicating FDC                                MDR7    0         Light on                                                            1         2 Hz blinking                                               ______________________________________                                    

What is claimed is:
 1. A camera adapted to function with film speeddata, comprising:first means for storing film speed data; second meansfor storing exposure time data; third means for storing aperture valuedata; fourth means for storing override data; first means for normallyindicating the stored exposure time data and also capable of indicatingthe stored film speed data in place of the exposure time data; andsecond means for normally indicating the stored aperture value data andalso capable of indicating the stored override data in place of theaperture value data.
 2. A camera adapted to function with film speeddata, comprising:first means for outputting film speed data; secondmeans for outputting exposure time data; third means for outputtingaperture value data; fourth means for outputting override data; firstmeans for normally indicating the exposure time data output by theexposure time data outputting means, and also capable of indicating thefilm speed data output by the film speed data outputting means in placeof the exposure time data; and second means for normally indicating theaperture value data output by the aperture value data outputting means,and also capable of indicating the override data output by the overridedata outputting means in place of the aperture value data.